package freightCalculator;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner reader=new Scanner(System.in);
        float p=reader.nextFloat();//每公里每吨货物的基本运费
        float s=reader.nextFloat();//路程
        float w=reader.nextFloat();//货物重量
        Result result=new Result(p,s,w);
        int a=(int)result.calculateFreight();
        int b=a%10;
        if(b<=4){
            a=a-b;
        }else if(b>=5){
            a=a-b+10;
        }
        System.out.println(a);
    }
}